1. Field of the Invention
The present invention relates to bindings for a gliding apparatus, in particular a toe piece for a touring ski and a gliding apparatus equipped with such a binding. The gliding apparatus can be a ski or a snowshoe, for example.
2. Background Information
Ski touring is an increasingly popular sporting activity and attracts a growing number of enthusiasts.
Ski touring involves climbing a mountain using touring skis. During the ascent phase, the skis are equipped with “sealskin” made of a synthetic material that prevents the skis from moving backwards. Moreover, these skis have a special binding device comprising a toe piece enabling the touring ski boots to pivot about a transverse axis located at the forefoot. This rotation enables the heel of the user to move away from the ski in order to exert an optimal thrust force during the ascent.
The document EP-0 199 098-B1 describes a touring ski binding whose toe piece includes two L-shaped tightening levers, each of which articulates about a longitudinal axis. These arms include tightening lugs adapted to cooperate with a touring ski boot. The two tightening levers are articulated by a spring-loaded mechanism in order to occupy two stable positions. A first stable position, so-called tightening position, corresponds to a configuration in which the tightening lugs cooperate with corresponding recessed portions arranged laterally in the front portion of the touring ski boot. This cooperation makes it possible to attach the boot by allowing only a rotational movement about an axis transverse to the ski. A second stable position, so-called open position, corresponds to a configuration in which the tightening levers are spaced apart so that the tightening lugs release the boot, which can then be separated from the touring ski.
Binding the front portion of the touring ski boot on a touring ski equipped with such a toe piece is carried out as follows. In a first step, the boot is positioned while the two tightening levers of the toe piece are spaced apart, in the open position. In a second step, strong pressure is exerted on the spring-loaded mechanism, using the front of the boot sole. This action on the mechanism enables the tightening levers to switch to their tightening position. The boot is then fixed to the toe piece because, in this position, the tightening lugs are housed in the corresponding recessed portions of the boot.
However, a skier quickly finds it difficult to engage the ski boots in these bindings. Indeed, it is necessary to present the boot with its recessed portions facing the lugs with a certain precision, which is not easy due, in particular, to the size of the ski boots, on the one hand, and the small size of the lugs of the toe piece and of the corresponding recessed housings of the boot, on the other hand.
A first solution has been provided by the document EP-1 559 457-B1, which describes an alternative to the previous solution, in which the boot has a groove beneath its connecting lateral recessed portions, whose function is to guide the boot when it is positioned in the vicinity of the tightening lug of the toe piece of the ski. The tightening lugs are thus guided within the grooves of the boot until facing the recessed portions provided for binding the boot.
Although this solution enables the boot to be engaged with a slight longitudinal offset of the sole, the binding still requires a relatively precise longitudinal positioning of the boot. This toe piece provides no assistance to the boot insertion.
Other known designs involve providing toe units, which may or may not be retractable, adapted to cooperate with the front of the boot in order to position the boot longitudinally in a relatively precise manner. Such toe units are described in the documents EP-2 392 388-A1, U.S. Pat. No. 8,544,869-B2, EP-2 300 111-A1, and U.S. Pat. No. 8,439,389-B2.
However, the design of these toe pieces has proven to be complex. The proposed retractable toe pieces pivot about a transverse axis located in front of the tightening levers. In one case, the retraction of the toe piece is directly associated with a locking lever. In another case, the retraction is carried out by the longitudinal translation of the toe piece. In a third case, the toe piece is not retractable. In the latter case, the solution includes two fixed lateral stops that are small in size so as not to hinder the rotation of the boot when it is in engagement with the toe piece. These lateral stops are not very efficient because they act on small contact zones. They are even less efficient when the ski is banked.